Federal prosecutors indicted Kaushansky, a native of Ukraine who immigrated to the United States in 1979 and worked as a nuclear engineer at Westinghouse, and Yevgeny Adamov, the former Russian minister, in May 2005 on charges including conspiracy, money laundering and tax evasion.

U.S. prosecutors accused the men of stealing from the U.S., other nations and corporations more than $9 million that was intended to improve nuclear technology in Russia.

Prosecutors also claimed Kaushansky owed $5.5 million in back taxes, but U.S. District Judge Maurice Cohill found Kaushansky owed only $63,000.

Kaushanksy's attorney, Fred Thieman, said Kaushansky and Adamov funneled money through banks around the world to keep it safe from Russia's volatile economic market and to pay impoverished Russian nuclear scientists.

"I was given an opportunity to help hundreds of Russian scientists and their families in dire need," Kaushansky said Thursday. "I think I did a lot of good, but in the process I made some mistakes. I admit to those mistakes. I am guilty."

Adamov, who was Russia's nuclear energy minister from 1998 until he was fired by President Vladimir Putin in 2001, was arrested in Switzerland in May 2005 after being indicted. U.S. officials sought to have him extradited to the U.S., but Russian officials opposed the idea. Swiss officials sent him back to Russia, where he faces abuse of power and fraud charges.

"Dr. Adamov will probably never be in the United States to have the charges against him resolved," Cohill said.

Shortly after Kaushansky pleaded guilty, Adamov told reporters in Moscow he was innocent of the charges in the United States.

Kaushansky also was fined $20,000 (EUR14,851) and sentenced to three years' probation.